High quality semiconductor material

Abstract

A hydrogenated, silicon based semiconductor alloy has a defect density of less than 10 16 cm −3 . The alloy may comprise a hydrogenated silicon alloy or a hydrogenated silicon-germanium alloy. Hydrogen content of the alloy is generally less than 15%, and in some instances less than 11%. The tandem photovoltaic devices which incorporate the alloy exhibit low levels of photo degradation. In some instances, the material is fabricated by a high speed VHF deposition process.

1 . A hydrogenated silicon-germanium semiconductor alloy having a defect density of less than 10 16  cm −3 . 
     
     
         2 . (canceled) 
     
     
         3 . The semiconductor alloy of  claim 1 , wherein the defect density is less than 8×10 15  cm −3 . 
     
     
         4 . The semiconductor alloy of  claim 1 , wherein the defect density is approximately 7×10 15  cm −3 . 
     
     
         5 . The semiconductor alloy of  claim 1 , wherein the hydrogen content thereof is less than 15%. 
     
     
         6 . The semiconductor alloy of  claim 1 , further characterized in that when said alloy comprises the i layer of a p-i-n type photovoltaic cell, that cell manifests a photo-induced degradation, under open circuit conditions, of less than 15% when exposed to A.M. 1.5 illumination for 1,000 hours at 50° C. 
     
     
         7 . The semiconductor alloy of  claim 1 , further characterized in that when said alloy comprises one of the i layers in a triple junction photovoltaic cell having an initial efficiency of at least 9%, that cell manifests a photo-induced degradation, under open circuit conditions, of less than 10% when exposed to A.M. 1.5 illumination for 1,000 hours at 50° C. 
     
     
         8 . (canceled) 
     
     
         9 . The semiconductor alloy of  claim 1 , wherein at least a portion of said semiconductor material has a microstructure configured as a plurality of columns separated by microvoids. 
     
     
         10 . A photovoltaic device which includes the semiconductor alloy of  claim 1 . 
     
     
         11 . A hydrogenated silicon based semiconductor alloy characterized in that when said alloy comprises the i layer of a p-i-n type photovoltaic cell, that cell manifests a photo-induced degradation, under open circuit conditions, of less than 15% when exposed to A.M. 1.5 illumination for 1,000 hours at 50° C. 
     
     
         12 . The semiconductor alloy of  claim 1 , wherein said alloy is an amorphous hydrogenated silicon-germanium alloy. 
     
     
         13 . A hydrogenated, silicon based semiconductor alloy characterized in that when it comprises one of the i layers in a triple junction photovoltaic cell having an initial efficiency of at least 9% that cell manifests a photo-induced degradation, under open circuit conditions, of less than 10% when exposed to A.M. 1.5 illumination for 1,000 hours at 500 C. 
     
     
         14 . (canceled) 
     
     
         15 . The semiconductor alloy of  claim 13 , further characterized in that it has a defect density of less than 8×10 15  cm −3 . 
     
     
         16 . The semiconductor alloy of  claim 13 , further characterized in that it has a defect density of approximately 7×10 15  cm −3 . 
     
     
         17 . The semiconductor alloy of  claim 13 , wherein the hydrogen content thereof is less than 15%. 
     
     
         18 . The semiconductor alloy of  claim 13 , wherein at least a portion of said semiconductor material has a microstructure configured as a plurality of columns separated by microvoids. 
     
     
         19 . A photovoltaic device which includes the semiconductor alloy of  claim 13 . 
     
     
         20 . A hydrogenated silicon based semiconductor alloy having a defect density of less than 10 16  cm −3 , wherein at least a portion of said semiconductor material has a microstructure configured as a plurality of columns separated by microvoids. 
     
     
         21 . The semiconductor alloy of  claim 20 , wherein the hydrogen content thereof is less than 15%.